DE102021109604A1 - Rotating electric machine - Google Patents

Abstract

A rotating electrical machine includes a polyphase armature coil that is wound on an armature core. The armature coil is formed from electrical conductor groups, each of which is a bundle of electrical conductor segments and has a pair of leg portions and a connecting portion that connects the leg portions. The connecting portion is bent radially with respect to a circumferential direction. The electrical conductor groups are paired in such a way that each pair of the electrical conductor groups consists of a first electrical conductor group and a second electrical conductor group, both of which belong to the same phase of the armature coil. The circumferential distance between the leg sections of the first electrical conductor group is greater than that between the leg sections of the second electrical conductor group. In each pair of the electrical conductor groups, the terminal portions of the first and second electrical conductor groups are arranged so that they axially overlap one another.

Description

BACKGROUND

1. Technical field

The present disclosure relates to rotating electrical machines.

2 Description of the prior art

Rotating electrical machines are known which comprise an armature with a polyphase armature coil which is wound on an armature core. In addition, a method of forming the armature coil is also known by: (1) inserting both leg portions of each of the substantially U-shaped coil segments into corresponding slots of the armature core from an axial side of the armature core; and (2) connecting each corresponding pair of those parts of the leg portions of the coil segments which protrude from the corresponding slots on the other axial side of the armature core (see, for example, Japanese Patent No. JP 5702179 B2 ).

More specifically, according to the known method, a substantially S-shaped part is formed in a head portion of each of the coil segments, thereby reducing the circumferential dimension of an intersection area in which the head portion radially crosses a coil end of the armature coil. As a result, it is possible to compactly overlap the head portions of the coil segments each extending from adjacent ones of the slots of the armature core, thereby reducing the size of the coil end of the armature coil.

SUMMARY

The inventors of the present application found the following problems in the known rotating electrical machines. That is, in practice it may be desirable to change the design specifications of the rotating electrical machines according to the required performance, such as reducing the outer diameter of the armature, increasing the number of slots formed in the armature core, increasing the thickness of the coil segments or increasing the number of coil segments. In this case, even with the known armature coil forming method, there would still be a limit in reducing the circumferential dimension of the crossing portion of the head portion of each coil segment; therefore, it may be impossible to flexibly make changes to the design specifications of the rotating electrical machines.

The present disclosure has been made in view of the above problems. It is therefore a primary object of the present disclosure to provide an electric rotating machine with an improved structure that enables the design specifications to be easily changed and the size of the electric rotating machine to be minimized.

According to the present disclosure, an electrical rotating machine is provided that includes an armature. The armature includes an annular armature core and a polyphase armature coil wound on the armature core. The anchor core has a plurality of slots arranged in a circumferential direction thereof. The armature coil is formed from a multiplicity of electrical conductor groups which are connected to one another. Each of the plurality of electrical conductor groups is formed from a bundle of a plurality of electrical conductor segments. In addition, each of the plurality of electrical conductor groups is substantially U-shaped and has a pair of leg portions and a connection portion. The pair of leg portions are each received in a corresponding pair of the slots of the anchor core and are located at different radial positions in the corresponding slots. The connecting portion extends on an axial side of the armature core to connect the pair of leg portions. The connecting portion has a bent part that is radially bent with respect to the circumferential direction. The plurality of electrical conductor groups are paired so that each pair of electrical conductor groups consists of a first electrical conductor group and a second electrical conductor group, both of which belong to the same phase of the armature coil. The circumferential distance between the pair of leg parts of the first electrical conductor group is greater than the circumferential distance between the pair of leg parts of the second electrical conductor group. In each pair of the electrical conductor groups, the terminal portions of the first and second electrical conductor groups are arranged so that they axially overlap one another.

With the above arrangement, it is possible to provide a larger distance between each circumferentially adjacent pair of the connecting portions of the electrical conductor groups than in the case of arranging the connecting portions of the first and second electrical conductor groups which do not axially overlap each other. As a result, it becomes easier to change the design specifications of the rotating electrical machine such as reducing the outer diameter of the armature, increasing the number of slots formed in the armature core, increasing the thickness of the electrical conductor segments, or increasing the Number of electrical conductor segments contained in each of the electrical conductor groups.

In addition, with the above arrangement, it becomes possible to reduce the distance between each axially adjacent pair of the terminal portions of the electrical conductor groups and thereby reduce the size of a coil end of the armature coil than in the case where the terminal portions of the first and second electrical conductor groups are arranged so that they do not axially overlap each other. Here the coil end is formed from all connection sections of the electrical conductor groups.

In order to arrange the connecting portions of the first and second electrical conductor groups so that they axially overlap each other, the electrical conductor groups are bent at the connecting portions in the same manner. This makes it possible to prevent interference between every adjacent pair of the connecting portions of the electrical conductor groups.

In addition, since the connecting portions of the first and second electric conductor groups arranged to axially overlap each other belong to a same phase of the armature coil, it becomes possible to suppress the occurrence of electric discharge even when the first and second electrical conductor group are accidentally brought into contact with one another.

In further exemplary embodiments, for each of the electrical conductor groups, the electrical conductor segments forming the electrical conductor group can be arranged on the pair of leg sections of the electrical conductor group in a predetermined order in the radial direction so that they are radially aligned with one another in the corresponding slots of the armature core. At the connection section of the electrical conductor group, the electrical conductor segments forming the electrical conductor group are arranged parallel to one another, the order in which the electrical conductor segments are arranged on the pair of leg sections of the electrical conductor group in the corresponding slots.

With the above arrangement, the electrical conductor segments can be bent in the same way, thereby facilitating the manufacture of the armature. In addition, the electrical conductor segments can be arranged along the circumferential direction on the connection section, as a result of which the axial width of the connection section is reduced.

The bent parts of the connection sections of the first electrical conductor groups can be arranged in alignment with one another in the circumferential direction. The circumferential distance between the bent parts of the connecting portions of the first electrical conductor groups can be set so that it is greater than or equal to the circumferential distance between the slots of the armature core and less than or equal to twice the circumferential distance between the slots. The bent parts of the connecting sections of the second electrical conductor groups can also be arranged in alignment with one another in the circumferential direction. The circumferential distance between the bent parts of the terminal sections of the second electrical conductor groups can also be set so that it is greater than or equal to the circumferential distance between the slots of the armature core and less than or equal to twice the circumferential distance between the slots.

With the above arrangement, it becomes possible to reduce the axial width of the coil end consisting of all terminal portions of the electrical conductor groups.

For each of the electrical conductor groups, one of the pair of leg portions of the electrical conductor group can be received in a radially outer part of a corresponding slot of the armature core and the other of the pair of leg portions can be received in a radially inner part of another corresponding slot of the armature core. For each of the electrical conductor groups, a radially extending part can be formed in the bent part of the connecting section of the electrical conductor group, in which the electrical conductor segments that form the electrical conductor group are arranged in the circumferential direction in alignment with one another. The radially extending parts of the connecting sections of the first electrical conductor groups can be arranged in alignment with one another in the circumferential direction; the radially extending parts of the connecting sections of the second electrical conductor groups can be arranged in alignment with one another in the circumferential direction. The following relationship is satisfied: Rc × 2 × π / S NxHc RC × 2 × π / (S / 2), where Rc is the distance from a central axis of the armature core to a radial center of each of the slots, S is the number of is slots formed in the armature core, N is the number of the electrical conductor segments included in each of the electrical conductor groups, and Hc is a radial thickness of each of the electrical conductor segments in the corresponding slots of the armature core.

With the above configuration, it becomes possible to more effectively reduce the axial width of the coil end composed of all the terminal portions of the electrical conductor groups.

A spacing can be provided between each circumferentially adjacent pair of the bent parts of the connecting sections of the electrical conductor groups.

The bent parts of the terminal sections are generally formed by bending the electrical conductor segments. Therefore, large stresses can be induced more easily at the bent parts of the connection sections and the insulating coatings of the electrical conductor segments are damaged more easily than at the other parts of the connection sections. However, with the spacing provided between each circumferentially adjacent pair of the bent parts of the connection sections of the electrical conductor groups, electrical insulation between different phases of the armature coil can still be ensured.

For each of the electrical conductor groups, one of the pair of leg portions of the electrical conductor group can be received in a radially outer part of a corresponding groove of the armature core and the other of the pair of leg portions can be received in a radially inner part of another corresponding groove of the armature core. The following relationship can be satisfied: Wcx2 <HcxN, where Wc is a circumferential width of each of the electrical conductor segments in the corresponding slots of the armature core, Hc is a radial thickness of each of the electrical conductor segments in the corresponding slots of the armature core, and N is the number of the electrical conductor segments contained in each of the electrical conductor groups.

With the above configuration, it becomes possible to reduce the axial width of the connecting portions of the electrical conductor groups more effectively.

The armature coil may be a three-phase coil with three phase windings connected in a star shape to define a neutral point therebetween. The first and second electrical conductor groups, which form the same one of the phase windings of the armature coil, can be connected in series with one another. The first electrical conductor groups can be connected closer to the neutral point than the second electrical conductor groups.

In the above configuration, the second electrical conductor groups have a higher electrical potential than the first electrical conductor groups. In addition, as described above, in each pair of the electrical conductor groups, the second electrical conductor group is arranged axially within the first electrical conductor group and covered by it. Consequently, it becomes possible to ensure a sufficient distance from the second electrical conductor group to other electrical conductor groups which belong to a different phase of the armature coil than the second electrical conductor group, whereby the insulation properties of the armature coil are improved.

At the connecting portions of each pair of the electrical conductor groups, an axially inner side face of the first electrical conductor group and an axially outer side face of the second electrical conductor group may be arranged in surface contact with one another.

With the above arrangement, it is possible to secure a larger contact area between the axially inner side surface of the first electrical conductor group and the axially outer side surface of the second electrical conductor group than in the case of the arrangement in point or line contact with each other. As a result, it is possible to suppress damage to the insulating coatings of the electrical conductor segments constituting the first and second electrical conductor groups due to contact between the connection portions.

Each of the electrical conductor segments may include a main body made of an electrically conductive material and an insulating coating covering the surface of the main body. The insulating jacket can be formed from an electrically insulating material with cavities or free spaces formed therein.

With the above configuration, when the insulating coatings of the electrical conductor segments are subjected to an external force or vibration, for example, the voids formed in the insulating coatings may collapse, thereby significantly deteriorating the insulating properties of the insulating coatings. As described above, however, the connecting portions of each pair of the electric conductor groups are arranged so as to axially overlap each other; The free space is provided between each circumferentially adjacent pair of the bent parts of the connecting sections of the electrical conductor groups. Consequently, although the insulating coating is formed of the electrically insulating material with clearances formed therein, it is still possible to secure the insulating properties of the insulating coatings.

At the connecting sections of each pair of electrical conductor groups, the electrical conductor segments that form the first electrical conductor group can each axially oppose the electrical conductor segments that form the second electrical conductor group and be arranged at a substantially constant distance from them.

With the above arrangement, it is possible to prevent the insulating coatings of the electrical conductor segments from being damaged while suppressing an increase in the axial width of the coil end formed from all the connecting portions of the electrical conductor groups.

Each of the electrical conductor groups can be formed from a bundle of three electrical conductor segments. The armature coil can be a three-phase coil with three phase windings connected to one another in a star shape. Each of the phase windings of the armature coil may include four winding units which are connected in parallel to one another and each include a pair of the first and second electrical conductor groups which are connected to one another in series. The plurality of slots of the armature core can consist of pairs of in-phase slots. Each pair of the in-phase slots consists of two slots which are adjacent in the circumferential direction and which correspond to an identical one of the phase windings of the armature coil. In each pair of the in-phase slots, the four winding units that form the corresponding phase winding of the armature coil can be arranged so that the number of leg sections of the electrical conductor groups of the four winding units received in one of the pair of in-phase slots is equal to the number of Is leg portions of the electrical conductor groups of the four winding units received in the other of the pair of in-phase slots.

With the above arrangement, the four winding units can be uniformly received in the pair of in-phase slots, thereby ensuring electromagnetic balance and suppressing the circulating current in the armature.

Figure list

• 1 FIG. 3 is a cross-sectional view of an electrical rotating machine in accordance with an exemplary embodiment.
• 2 Fig. 13 is a plan view of a stator of the rotating electrical machine.
• 3 Fig. 13 is a schematic diagram showing the configuration of a stator core and a stator coil of the stator.
• 4A and 4B 12 are perspective views each showing, from opposite sides in an axial direction, a pair of first and second electrical conductor groups for forming the stator coil.
• 5A and 5B 12 are perspective views showing the pair of the first and second electrical conductor groups from a radial side and an axial side, respectively.
• 6th Fig. 3 is an enlarged cross-sectional view of an electrical conductor segment.
• 7th Fig. 13 is an enlarged perspective view of turn portions of electrical conductor groups constituting the stator coil.
• 8th is a schematic representation of the arrangement of electrical conductor segments on the turn portions of the electrical conductor groups.
• 9 Fig. 13 is a perspective view showing the electrical conductor groups being assembled and the stator core before the electrical conductor groups are inserted into the slots of the stator core.
• 10 Fig. 13 is a perspective view showing the electrical conductor groups and the stator core after the electrical conductor groups are inserted into the slots of the stator core.
• 11 A Fig. 13 is a perspective view of part of the stator developed in a circumferential direction.
• 11B Fig. 13 is a plan view of a portion of the stator developed in the circumferential direction.
• 12A Fig. 13 is a schematic diagram showing the arrangement of a pair of first and second electrical conductor groups in the corresponding slots of the stator core.
• 12B Fig. 13 is a schematic diagram showing the arrangement of the electrical conductor segments used in Figs 12A Form shown first electrical conductor group in the corresponding slots of the stator core shows.
• 13th Fig. 13 is a schematic diagram showing the connection diagram of a U-phase winding of the stator coil.
• 14th Figure 3 is a schematic diagram of the stator coil.
• 15A Fig. 13 is an enlarged cross-sectional view of an electrical conductor segment according to a first modification.
• 15B Fig. 13 is an enlarged cross-sectional view of another electrical conductor segment according to the first modification.
• 16A Figure 13 is a schematic illustration showing a desirable arrangement of electrical conductor segments on the Shows turn portions of the electrical conductor groups according to a second modification.
• 16B Fig. 13 is a schematic diagram showing another desirable arrangement of electrical conductor segments on the turn portions of the electrical conductor groups according to the second modification.
• 16C Fig. 13 is a schematic diagram showing an undesirable arrangement of electrical conductor segments on the turn portions of the electrical conductor groups according to the second modification.
• 17A and 17B 13 are schematic diagrams collectively illustrating an example in which each phase winding of the stator coil is configured as a short pitch winding which is wave-wound according to a third modification.
• 18A Fig. 13 is a schematic diagram showing an example in which each phase winding of the stator coil is configured as a full-pitch wave-wound winding according to the third modification.
• 18B Fig. 13 is a schematic diagram showing an example in which each phase winding of the stator coil is configured as a short pitch wave-wound winding according to the third modification.
• 19A Fig. 13 is a schematic diagram showing an example in which each phase winding of the stator coil is configured as a full-pitch lap-wound winding according to the third modification.
• 19B Fig. 13 is a schematic diagram showing an example in which each phase winding of the stator coil is configured as an overlap-wound short pitch winding according to the third modification.
• 20A , 20B and 20C Fig. 13 are schematic illustrations showing alternative cross-sectional shapes of the electrical conductor segments according to a fourth modification.
• 21 Fig. 13 is a schematic circuit diagram of a stator coil according to a fifth modification.
• 22nd Fig. 13 is a perspective view showing jumper wires used in a stator according to a sixth modification.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Exemplary embodiments are described below with reference to the drawings. It is pointed out that, for the sake of clarity and understanding, identical components with identical functions throughout the description are, as far as possible, marked with the same reference symbols in the drawings and that descriptions of identical components are not repeated to avoid redundancy.

1 shows the overall structure of a rotating electrical machine according to an exemplary embodiment.

In the present exemplary embodiment, the rotating electrical machine is an electric motor 10 configured for use in a vehicle. In particular is the electric motor 10 a three-phase permanent magnet synchronous motor. That is, the electric motor 10 is a brushless motor. In addition, the electric motor can 10 comprise either only one three-phase coil belonging to a single system or two three-phase coils each belonging to two systems.

As in 1 shown includes the electric motor 10 a housing 20th , a stator 30th attached to the housing 20th is attached and acts as an anchor in the present embodiment, a rotor 40 that is configured to be relative to the stator 30th rotates, and a rotating shaft 11 at which the rotor 40 is attached.

In addition, the following is the direction in which a central axis O of the rotating shaft 11 extends, denoted as the axial direction (in the drawings by a double-headed arrow Y1 displayed); the directions extending radially from the central axis O of the rotating shaft 11 are referred to as radial directions (in the drawings by a double-headed arrow Y2 displayed); and the direction extending along a circle whose center is on the central axis O of the rotating shaft 11 is referred to as the circumferential direction (in the drawings by a double-headed arrow Y3 displayed).

The case 20th is cylindrical in shape and has both the stator 30th as well as the rotor 40 included in it. In the case 20th is a pair of bearings 23 and 24 provided by the rotating shaft 11 is rotatably mounted. In addition, the axis of an inner peripheral surface of the housing falls 20th with the central axis O of the rotating shaft 11 together.

The rotor 40 is part of one in the electric motor 10 formed magnetic circuit. The rotor 40 has one or more magnetic pole pairs arranged in the circumferential direction and is the stator 30th arranged radially opposite one another. In particular, the rotor has 40 in the present embodiment, twelve magnetic poles (ie the number of magnetic pole pairs of the rotor 40 equals 6). In addition, the number of magnetic poles of the rotor 40 alternatively on other values according to the design specifications of the electric motor 10 can be set.

The rotor 40 includes a rotor core formed from a magnetic material 41 and on the rotor core 41 fixed permanent magnets 42 .

In particular, the rotor comprises 40 in the present embodiment, twelve permanent magnets 42 whose polarities are alternately different in the circumferential direction. The permanent magnets 42 are each embedded in twelve magnet mounting holes in the rotor core 41 are formed along the axial direction. That is, in the present embodiment, the rotor is 40 designed as an IPM rotor (internal permanent magnet). Alternatively, the rotor 40 be configured as an SPM (surface permanent magnet) rotor. Another alternative is the rotor 40 be configured as a field coil type rotor.

In a central hole in the rotor core 41 is the rotating shaft 11 firmly inserted so that the rotor 40 together with the rotating shaft 11 around the central axis O of the rotating shaft 11 can turn.

The stator 30th is cylindrically shaped and in a substantially axially central part of the housing 20th along the inner peripheral surface of the housing 20th arranged. Also is the stator 30th on the inner peripheral surface of the housing 20th attached so that a central axis of the stator 30th with the central axis O of the rotating shaft 11 coincides.

The stator 30th also forms part of that in the electric motor 10 formed magnetic circuit. As in 2 shown has the stator 30th an annular stator core (or armature core) 31 that is radially outside of the rotor 40 is arranged so that it is the rotor 40 facing radially, and a three-phase stator coil (or armature coil) 32 that are on the stator core 31 is wrapped.

It should be noted that when depicting the stator coil 32 in the drawings of the edge lines which represent boundaries between surfaces with different orientations, only those are shown which are used for the representation of the three-dimensional shape of the stator coil 32 are particularly important. In addition, it should be noted that those of the edge lines that form the radially outer contour of the stator coil 32 represent, in the drawings are shown with solid lines.

As in 3 shown includes the stator core 31 an annular rear yoke (or rear core) 33 and a plurality of teeth 34 , which are arranged at predetermined intervals in the circumferential direction and each radially inward from the rear yoke 33 protrude. Between each circumferentially adjacent pair of teeth 34 is a slot 35 educated. That is, in the stator core 31 is a variety of slots 35 formed at equal intervals in the circumferential direction. The stator coil 32 is so on the teeth 34 wrapped them in the slots 35 is recorded. In addition, the number of teeth 34 equal to the number of slots 35 .

In the present embodiment, the number of slots is 35 (or the number of teeth 34 ) per magnetic pole of the rotor 40 that has the twelve magnetic poles, and per phase of the three-phase stator coil 32 2. In other words, the slot multiplier number is 2. Accordingly, the total number is in the stator core 31 formed slots 35 equal to 72 (i.e. 2 × 12 × 3). In addition, there are 72 slots 35 of pairs of U-phase slots Su1 and Su2, V-phase slots Sv1 and Sv2, and W-phase slots Sw1 and Sw2, which are sequentially and repeatedly arranged in the circumferential direction (see FIG 12A ).

In the present embodiment, there is the stator core 31 a laminate formed by laminating a plurality of annular magnetic steel sheets (or core sheets) in the axial direction. In addition, the stator core 31 alternatively consist of a plurality of stator core segments which are arranged adjacent to one another in the circumferential direction.

The stator coil 32 consists of U-phase, V-phase and W-phase windings that are star-connected (or Y-connected) to define a neutral point in between (see 14th ). The stator coil generates during operation 32 a magnetic flux when supplied with three-phase AC voltage.

In the present embodiment, the stator coil 32 formed by from a first axial side of the stator core 31 made up of a plurality of substantially U-shaped electrical conductor segments 52 into the slots 35 of the stator core 31 is inserted and each corresponding pair of end portions of the electrical conductor segments 52 coming out of the slots 35 protrude on a second axial side of the stator core 31 is connected. Each of the electrical conductor segments 52 is obtained by cutting and plastically deforming an electrical conductor having a substantially rectangular cross-sectional shape and a constant thickness into the substantially "U" shape.

In particular, in the present embodiment, as shown in FIG 4A and 4B shown each of the phase windings of the stator coil 32 from a variety of substantially U-shaped electrical conductor groups 51 educated. The electrical conductor groups 51 include two types of electrical conductor groups 51 that are of different sizes and overlap in pairs. Any pair of electrical conductor groups 51 consists of a first group of electrical conductors 51a , which is located on the outside, and a second electrical conductor group 51b which is located on the inside. For each pair of electrical conductor groups 51 are both the first and the second electrical conductor group 51a and 51b of the pair are connected to the same one of the U-phase, V-phase and W-phase terminals so that they become the same of the U-, V- and W-phases of the stator coil 32 belong. In addition, are 4A and 4B perspective views showing a pair of the first and second electrical conductor groups 51a respectively. 51b Pointing from opposite sides in the axial direction before they are on the stator core 31 to be assembled.

In addition, as in the 5A and 5B shown each of the electrical conductor groups 51 from a plurality (for example four in the present exemplary embodiment) of essentially U-shaped electrical conductor segments 52 that are bundled together. In addition, are 5A and 5B perspective views showing a pair of the first and second electrical conductor groups 51a respectively. 51b from a radial side and an axial side show before being attached to the stator core 31 to be assembled. It should also be noted that, for the sake of simplicity, the electrical conductor segments 52 each of the electrical conductor groups 51 in the drawings with the exception of 5A and 5B are not shown individually.

As in 3 shown have the electrical conductor segments 52 a substantially rectangular cross-sectional shape. In each of the slots 35 of the stator core 31 are the electrical conductor segments 52 aligned radially in a row so that the longer sides of the rectangular cross-sections of the electrical conductor segments 52 facing each other radially.

Referring to 3 is each of the electrical conductor groups in the present embodiment 51 configured so as to satisfy the following relationship: Wcx2 <Hc × N, where Wc is the circumferential width of each of the electrical conductor segments 52 in the corresponding slots 35 of the stator core 31 , Hc is the radial thickness of each of the electrical conductor segments 52 in the corresponding slots 35 of the stator core 31 and N is the number of electrical conductor segments 52 is that in each of the electrical conductor groups 51 are included.

In addition, in the present embodiment, each of the electrical conductor groups 51 by bending the electrical conductor segments 52 the group 51 which are in a state of bundling are formed into the substantially "U" shape using molding tools.

As in 6th shown includes each of the electrical conductor segments 52 a main body 52a , which is formed from an electrically conductive material (e.g. copper), and an insulating coating 52b that is the surface of the main body 52a covered. In the present exemplary embodiment, the insulating coating is 52b formed from an electrically insulating material (e.g., resin) with clearances formed therein.

As in the 4th and 5 each of the electrical conductor groups has shown 51 a pair of straight sections (or leg sections) 53 each in a pair of the slots 35 which are circumferentially spaced from each other by a predetermined distance, and a winding portion (or connecting portion) 54 showing the pair of straight sections 53 connects.

The straight sections 53 are shaped to extend straight in the axial direction. The straight sections 53 are arranged parallel to one another and at a predetermined distance from one another. The axial length of the straight sections 53 is set to be larger than the axial length of the stator core 31 . Each of the straight sections 53 is in a corresponding one of the slots 35 of the stator core 31 received with both ends thereof axially out of the corresponding groove 35 stick out. In addition, the distance is L1 between the straight sections 53 the first group of electrical conductors 51a greater than the distance L2 between the straight sections 53 the second electrical conductor group 51b set.

For each of the electrical conductor groups 51 (ie the first and second electrical conductor group 51a and 51b ) becomes the pair of straight sections 53 the electrical conductor group 51 each in the corresponding slots 35 of the stator core 31 added so that they differ from each other in their radial position. More precisely, as in the 12A and 12B becomes one of the pair of straight sections 53 in a radially outer part of a corresponding slot 35 of the stator core 31 while the other of the pair of straight sections 53 in a radially inner part of another corresponding slot 35 of the stator core 31 is recorded.

Also are for each of the electrical conductor groups 51 the electrical conductor segments 52 who have favourited the electrical conductor group 51 form on the pair of straight sections 53 the electric Leader group 51 arranged in a predetermined arrangement order in the radial direction so that they are in the corresponding slots 35 are aligned radially to each other. For example, the electrical conductor segments 52 at one of the in 12 (B) illustrated pairs of straight sections 53 in the order U1a → U1b → U1c → U1d from the radially inner side in the corresponding groove 35 arranged; at the other of the in 12 (B) illustrated pairs of straight sections 53 are the electrical conductor segments 52 also in the order U1a → U1b → U1c → U1d from the radially inner side in the corresponding groove 35 arranged.

As in 2 and 4A-4B shown is in each of the electrical conductor groups 51 (ie the first and second electrical conductor group 51a and 51b ) the winding section 54 formed so that it extends in the circumferential direction and at its peripheral ends with the axial ends of the straight sections 53 connected is. As in 7th shown is the winding section 54 also shaped so that it has the shape of a web which is higher in its circumferential center than at its circumferential ends. The peripheral end parts of the turn portion 54 are each with the straight sections 53 connected so that they are at a predetermined angle to the direction of extension of the straight sections 53 (or inclined to the axial direction). More precisely, as in 4A and 7th is shown, each of the peripheral end parts of the turn portion 54 obliquely to the direction of extent of the straight sections 53 (or the axial direction) so that an angle α between the peripheral end part and the extending direction of the straight portions 53 is equal to the predetermined angle (e.g., about 120 °). In addition, the predetermined angle is set to be for both the first and second electrical conductor groups 51a and 51b is equal to.

As in 12A and 12B shown, connects the winding portion 54 also the pair of straight sections 53 that are in different radial positions. Therefore the winding section has 54 , as in 2 is shown a bent portion which, when viewed in the axial direction, bends (or is bent) substantially into an "S" shape. In addition, as in the 4A-4B and 7th shown each of the electrical conductor groups 51 bent so that an axially inner side surface of the turn portion 54 the electrical conductor group 51 with the circumferentially inner side surfaces of the straight sections 53 the electrical conductor group 51 is connected, an axial end face of the stator core 31 opposite.

More precisely, in each of the electrical conductor groups 51 (ie the first and second electrical conductor group 51a and 51b ) has the winding section 54 a first peripheral end coincident with that of the pair of straight sections 53 which is located radially inward, and a second peripheral end that is connected to that of the pair of straight sections 53 is connected, which is located radially outward. The winding section 54 extends along the circumferential direction from the first circumferential end to the vicinity of a central part thereof. In addition, the winding section has 54 as in the 2 and 7th shown a first bend 55 from the radially inner side to the radially outer side with respect to the circumferential direction in the vicinity of the central part of the winding portion 54 is bent. The first bend 55 is bent to the extent that the winding section 54 becomes parallel to the radial direction, ie to the extent that all electrical conductor segments 52 showing the winding section 54 form, are aligned with one another in the circumferential direction.

Hence, as in 2 and 7-8 shown near the central part of the coil section 54 a radially extending part 56 which extends along the radial direction. Also, as in 7th shown the radially extending portion 56 an apex part of the turn portion 54 which is farthest axially from the stator core 31 in the turn section 54 is located. That is, in the area from the first peripheral end to the radially extending part 56 extends the turn portion 54 oblique to the axial direction and away from the stator core 31 .

In addition, as in 2 shown the radially extending portion 56 with a second bend 57 of the winding section 54 which is bent from the radial direction toward the circumferential direction. More specifically, is the second bend 57 bent at an acute angle in the shape of a hairpin curve, leaving part of the second bend 57 radially outward from the slots 35 of the stator core 31 protrudes. From the second bend 57 extends the turn portion 54 along the circumferential direction up to its second circumferential end. In addition, as in 7th shown in the region of the radially extending part 56 up to the second circumferential end of the winding section 54 obliquely with respect to the axial direction and towards the stator core 31 .

In the present embodiment, the radius of curvature (or radius of curvature R) is the second bend 57 set smaller than the radius of curvature of the first bend 55 . Therefore it is in the winding section 54 a bend with a smaller radius of curvature (i.e. the second bend 57 ) located more radially outward than a bend with a larger radius of curvature (ie the first bend 55 ).

In addition, as in 2 shown, the protruding amount of the second bend 57 (i.e. the amount by which the second bend 57 radially out of the slots 35 of the stator core 31 protruding) adjusted to be within the range of the posterior yoke 33 of the stator core 33 lies. That is, the protruding amount is set so that the entire second bend is 57 radially inside the radially outer periphery of the stator core 31 is located.

On the other hand, as in 2 shown the first bend 55 not radially inwards out of the slots 35 of the stator core 31 out. That is, the amount by which the coil section 54 radially outward from the slots 35 of the stator core 31 protrudes is set so that it is larger than the amount by which the winding portion 54 radially inwards out of the slots 35 protrudes. In other words, the stator coil 32 bulges only radially outward, not radially inward, out of the slots 35 of the stator core 31 .

As described above, in the present embodiment, form the first bend 55 , the radially extending part 56 and the second bend 57 together the substantially S-shaped bent part of the rotating part 54 .

In addition, in the present embodiment, the rotor 40 configured to rotate in a predetermined direction of rotation included in 2 indicated by a hidden arrow (i.e. the counterclockwise direction in 2 ). In each of the electrical conductor groups 51 (ie the first and second electrical conductor group 51a and 51b ) the winding section extends 54 radially outward while moving in the direction of rotation of the rotor 40 extends. That is, of the pair of peripheral ends of the turn portion 54 is the second peripheral end on the radially outer side in the rotating direction of the rotor 40 arranged in front of (downstream) from the first peripheral end on the radially inner side.

As in 4th and 7th are shown for each pair of the first and second electrical conductor groups 51a and 51b the turn sections 54 the first and second electrical conductor groups 51a and 51b arranged so that they overlap each other in the axial direction. In addition, there is the winding section 54 the second electrical conductor group 51b on the axially inner side (or the side of the stator core 31 ) of the winding section 54 the first group of electrical conductors 51a . In addition, the winding sections 54 the first and second electrical conductor groups 51a and 51b arranged so that an axially inner side surface of the turn portion 54 the first group of electrical conductors 51a an axially outer side surface of the turn portion 54 the second electrical conductor group 51b facing and spaced at a substantially constant distance therefrom. That is, the winding sections 54 the first and second electrical conductor group 51a and 51b are arranged so that they extend parallel to each other.

More precisely, as in 4A and 7th shown are the oblique angles α of the winding section 54 to the straight sections 53 in the first electrical conductor group 51a essentially equal to the oblique angles α of the winding section 54 to the straight sections 53 in the second electrical conductor group 51b . Beyond that is the first bend 55 , the radially extending part 56 and the second bend 57 in the winding section 54 the first group of electrical conductors 51a each at substantially the same circumferential positions as the first bend 55 , the radially extending part 56 and the second bend 57 in the winding section 54 the second electrical conductor group 51b . In addition, these are the radius of curvature of the first bend 55 , the length of the radially extending portion 56 and the radius of curvature of the second bend 57 in the winding section 54 the first group of electrical conductors 51a adjusted so that they each substantially equal the radius of curvature of the first bend 55 , the length of the radially extending part 56 and the radius of curvature of the second bend 57 in the winding section 54 the second electrical conductor group 51b are. That is, the bent part of the turn portion 54 the first group of electrical conductors 51a and the bent part of the turn portion 54 the second electrical conductor group 51b have essentially the same "S" shape.

With the above configuration, as in 8th shown are the electrical conductor segments 52 who have favourited the first electrical conductor group 51a and 51b form, at the turn sections 54 each pair of the first and second electrical conductor groups 51a and 51b parallel to the electrical conductor segments 52 arranged that the second electrical conductor group 51b form. In addition, the axially inner side surfaces (i.e. the lower side surfaces in 8th ) of the electrical conductor segments 52 who have favourited the first electrical conductor group 51a each form the axially outer side surfaces (i.e. the upper side surfaces in 8th ) of the electrical conductor segments 52 who have favourited the second electrical conductor group 51b form, axially opposite and arranged at a substantially constant distance from them.

In addition, the axially inner Side surfaces of the electrical conductor segments 52 who have favourited the first electrical conductor group 51a form, alternatively in surface contact with the axially outer side surfaces of the electrical conductor segments 52 who have favourited the second electrical conductor group 51b form, be arranged. That is, the axially inner side surfaces of the electrical conductor segments 52 who have favourited the first electrical conductor group 51a may not form from the axially outer side surfaces of the electrical conductor segments 52 who have favourited the second electrical conductor group 51b form, be spaced.

In addition, as in 2 shown, the substantially S-shaped bent parts of the winding sections 54 of the electrical conductor groups 51 arranged in alignment with one another in the circumferential direction. In the present embodiment, the circumferential distance between the bent parts is the turn portions 54 of the electrical conductor groups 51 adjusted to be greater than or equal to the circumferential distance between the slots 35 of the stator core 31 and less than or equal to twice the circumferential spacing between the slots 35 is.

More precisely, as in the 2 and 7th shown the radially extending parts 56 of the winding sections 54 of the first electrical conductor groups 51a arranged in alignment with one another in the circumferential direction. The circumferential distance between the radially extending parts 56 of the winding sections 54 the first group of electrical conductors 51a is set to be greater than or equal to the circumferential distance between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35 is. Similarly, are the radially extending parts 56 of the winding sections 54 of the second electrical conductor group 51b also arranged in alignment with one another in the circumferential direction. The circumferential distance between the radially extending parts 56 of the winding sections 54 the second electrical conductor group 51b is also set to be greater than or equal to the circumferential distance between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35 is.

wobei Rc der Abstand von einer Mittelachse des Statorkerns 31 (oder der Mittelachse O der rotierenden Welle 11) zur radialen Mitte jedes der Schlitze 35 ist, S die Anzahl der im Statorkern 31 ausgebildeten Schlitze 35 ist, N die Anzahl der elektrischen Leitersegmente 52 ist, die in jeder der elektrischenAlso, between each circumferentially adjacent pair of the radially extending parts 56 of the winding sections 54 of the electrical conductor groups 51 a predetermined distance C1 intended. In the present embodiment, the stator 30th configured to meet the following relationship: $$\text{Rc}\times 2\times \mathrm{\pi }/\text{S.}\le \text{N}\times \text{Hc}\le \text{Rc}\times 2\times \mathrm{\pi }/\left(\text{S.}/2\right)$$

where Rc is the distance from a central axis of the stator core 31 (or the central axis O of the rotating shaft 11 ) to the radial center of each of the slots 35 is, S is the number of in the stator core 31 formed slots 35 is, N is the number of electrical conductor segments 52 is that in each of the electrical

Leader groups 51 are included, and Hc is the radial thickness of each of the electrical conductor segments 52 in the corresponding slots 35 of the stator core 31 is.

In addition, the distance Rc in 2 and 3 shown. How out 2 As can be seen, the distance Rc can be taken as the distance from the central axis of the stator core 31 to the radial center position of the radially extending parts 56 of the winding sections 54 of the electrical conductor groups 51 to be viewed as. In addition, how out 3 As can be seen, the distance Rc is also called the distance from the central axis of the stator core 31 to the boundary between the two groups of electrical conductors 51 in each of the slots 35 to be viewed as. The radial thickness Hc of each of the electrical conductor segments 52 is in 3 shown. In addition, how exhibits 8th As can be seen, N × Hc is the circumferential dimension of each of the radially extending portions 56 (or the apex parts) of the winding sections 54 of the electrical conductor groups 51 represent.

Referring again to the 2 and 7th are the first bends 55 of the winding sections 54 the first group of electrical conductors 51a arranged in alignment with one another in the circumferential direction. The circumferential distance between the first bends 55 of the winding sections 54 the first group of electrical conductors 51a is set to be greater than or equal to the circumferential distance between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35 is. The first bends are similar 55 of the winding sections 54 the second electrical conductor group 51b also arranged in alignment with one another in the circumferential direction. The circumferential distance between the first bends 55 of the winding sections 54 the second electrical conductor group 51b is also set to be greater than or equal to the circumferential distance between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35 is.

Also, the second are bends 57 of the winding sections 54 the first group of electrical conductors 51a arranged in alignment with one another in the circumferential direction. The circumferential distance between the second bends 57 of the winding sections 54 the first group of electrical conductors 51a is set to be greater than or equal to the circumferential distance between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35 is. The second bends are similar 57 of the winding sections 54 the second electrical conductor group 51b arranged in alignment with one another in the circumferential direction. The circumferential distance between the second bends 57 of the winding sections 54 the second electrical conductor group 51b is also set to be greater than or equal to the circumferential distance between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35 is.

In the present embodiment, as shown in FIG 12B shown for each of the electrical conductor groups 51 the electrical conductor segments 52 who have favourited the electrical conductor group 51 form, at the turn portion 54 the electrical conductor group 51 arranged parallel to each other, the order of the arrangement of the electrical conductor segments 52 at the pair of straight sections 53 the electrical conductor group 51 in the corresponding slots 35 of the stator core 31 is retained.

As in 9 are shown, the straight sections 53 each axially overlapping pair of the first and second electrical conductor groups 51a and 51b from the first axial side (i.e. the upper side in 9 ) of the stator core 41 into the corresponding slots 35 of the stator core 31 introduced. Then the distal end parts become the straight sections 53 that are on the second axial side (i.e. the lower side in 10 ) of the stator core 31 from the corresponding slots 35 protrude, twisted and bent along the circumferential direction at a predetermined distance, thereby connecting portions 58 are formed.

As in 11 and 13th as shown, each of the connecting portions includes 58 a first connection section 58a that is circumferentially outward from a corresponding pair of the straight sections 53 is bent, and a second connecting portion 58b that is circumferentially inward from a corresponding pair of the straight sections 53 is bent.

In addition, is 11A a perspective view of part of the stator 30th in the circumferential direction. 11B Figure 3 is a plan view of part of the stator 30th developed in the circumferential direction. It should be noted that, for the sake of simplicity, only some of the connecting sections 58 in the 11A and 11B are shown and that in fact all slots 35 of the stator core 31 the corresponding straight sections 53 of the electrical conductor groups 51 received therein and the corresponding connecting portions 58 protruding from it.

The bending directions of the connection sections 58a and 58b are based on a predetermined connection pattern of the stator coil 32 for the electrical conductor segments 52 who have favourited the electrical conductor groups 51 form varies. Also, the way is how the bending directions of the connector sections 58a and 58b for the electrical conductor segments 52 can be varied in the 11A and 11B shown.

Each corresponding pair of the connector sections 58a and 58b of the electrical conductor groups 51 are connected to one another, for example, by TIG welding, laser welding, ultrasonic welding or the like. Consequently, the terminal sections 58 with the stator core 31 engaged and secured in the axial direction; thus are the electrical conductor groups 51 through the connection sections 58 and the turning sections 54 on the stator core 31 attached. This will make the straight sections 53 of the electrical conductor groups 51 an axial movement relative to the stator core 31 prevented and therefore reliable in the corresponding slots 35 of the stator core 31 held.

In addition, the electrical conductor groups are 51 through the connection sections 58 electrically connected in the predetermined connection pattern and form the U-phase, V-phase and W-phase windings of the stator coil 32 .

Next is the connection diagram of the stator coil 32 with reference to 12A-12B and 13th described in detail.

12A Fig. 11 illustrates the arrangement of a pair of first and second electrical conductor groups 51a and 51b in the corresponding slots 35 of the stator core 31 . 12B illustrates the arrangement of the electrical conductor segments 52 that the in 12A shown first electrical conductor group 51a form in the corresponding slots 35 of the stator core 31 . 13th illustrates the connection diagram of the U-phase winding of the stator coil 32 . In addition, in 12A and 13th the first group of electrical conductors 51a shown with solid lines, while the second electrical conductor group 51b is shown with dashed lines.

In the present embodiment, as shown in 12A-12B and 13th each phase winding is the stator coil 32 configured as a distributed winding.

In addition, as in the 12A-12B shown for each of the electrical conductor groups 51 (ie the first and second electrical conductor groups 51a and 51b ) one of the pair of straight sections 53 the electrical conductor group 51 in a radially outer part of a corresponding slot 35 added while the other of the pair of straight sections 53 in a radially inner part of another corresponding slot 35 is recorded. Also is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed with a 7-slot pitch, while the winding section 54 the second electrical conductor group 51b is designed with a 5-slot pitch.

As in 13th are shown in each of the electrical conductor groups 51 the pairs of straight sections 53 located at different radial positions through the winding portion 54 on the first axial side (i.e. the upper side in 13th ) of the stator core 31 tied together. On the other hand, on the second axial side (i.e. the lower side in 13th ) of the stator core 31 each corresponding pair of the straight sections 53 belonging to different of the electrical conductor groups 51 and are at the same radial position by one of the connecting sections 58 tied together.

In addition, as in 13th shown each phase winding of the stator coil 32 on the stator core 31 wound in a distributed winding manner, particularly in a wave-lobe winding manner. In addition, each phase winding is the stator coil 32 designed as a full-spaced winding, the pitch of which is equal to the pitch of the magnetic pole.

As described above, in the present embodiment, as shown in FIG 14th shown, the U-phase, V-phase and W-phase windings of the stator coil 32 Connected in a star shape to define the neutral point in between. In addition, the first and second electrical conductor groups are 51a and 51b that are an equal of the U-phase, V-phase and W-phase windings of the stator coil 32 form, connected in series with each other. In addition, the first are electrical conductor groups 51a connected closer to the star point than the second electrical conductor groups 52 .

According to the present embodiment, it is possible to obtain the following advantageous effects.

In the present exemplary embodiment, the electric motor comprises 10 the stator 30th (or anchor). The stator 30th includes the stator core 31 (or annular armature core) and the three-phase stator coil 32 (or armature coil) around the stator core 31 is wrapped. The stator core 31 has a multitude of slots 35 which are arranged in its circumferential direction. The stator coil 32 is made up of a large number of interconnected electrical conductor groups 51 educated. Each of the electrical conductor groups 51 consists of a bundle of a multiplicity (for example four in the present exemplary embodiment) of electrical conductor segments 52 . Any of the wide variety of electrical conductor groups 51 is essentially U-shaped, around the pair of straight sections 53 (or leg sections) and the winding section 54 (or connecting section). The pair of straight sections 53 is each in a corresponding pair of the slots 35 of the stator core 31 added so that it is at different radial positions in the corresponding slots 35 is located. The winding section 54 extends on the first axial side of the stator core 31 to get the pair of straight sections 53 connect to. The winding section 54 has the substantially S-shaped bent part that is radially bent with respect to the circumferential direction. The variety of electrical conductor groups 51 are paired so that each pair of electrical conductor groups 51 from a first group of electrical conductors 51a and a second group of electrical conductors 51b consists, both of which are at the same phase of the stator coil 32 belong. The circumferential distance between the pair of straight sections 53 the first group of electrical conductors 51a is greater than the circumferential distance between the pair of straight sections 53 the second electrical conductor group 51b . In each pair of the electrical conductor groups 51 are the winding sections 54 the first and second electrical conductor groups 51a and 51b arranged so that they axially overlap each other.

With the above arrangement, it becomes possible to have a larger distance between each circumferentially adjacent pair of the turn portions 54 of the electrical conductor groups 51 than in the case of the arrangement of the winding sections 54 the first and second electrical conductor groups 51a and 51b that do not overlap axially. As a result, it becomes easier to check the design specifications of the electric motor 10 change, such as reducing the outside diameter of the stator 30th , increasing the number of in the stator core 31 formed slots 35 , increasing the thickness of the electrical conductor segments 52 or increasing the number of electrical conductor segments 52 that are in each of the electrical conductor groups 51 are included.

In addition, with the above arrangement, it becomes possible to adjust the distance between each axially adjacent pair of the turn portions 54 of the electrical conductor groups 51 to reduce and thereby the size of a coil end of the stator coil 32 to reduce than in the case where the winding sections 54 the first and second electrical conductor groups 51a and 51b are arranged so that they do not axially overlap each other. In addition, the coil end is made up of all winding sections 54 of the electrical conductor groups 51 educated.

Around the turn sections 54 the first and second electrical conductor groups 51a and 51b to be arranged so that they axially overlap each other, the electrical conductor groups 51 at the respective winding sections 54 bent in the same way. As a result, it becomes possible for noises to occur between each adjacent pair of the turn portions 54 of the electrical conductor groups 51 to prevent.

Since, in addition, the winding sections 54 the first and second electrical conductor groups 51a and 51b which are arranged so as to axially overlap each other at an equal phase of the stator coil 32 belong, it becomes possible to suppress the occurrence of electric discharge even if the first and second electric conductor groups 51a and 51b accidentally brought into contact with each other.

In the present exemplary embodiment are for each of the electrical conductor groups 51 the electrical conductor segments 52 who have favourited the electrical conductor group 51 form on the pair of straight sections 53 the electrical conductor group 51 arranged in the predetermined arrangement order in the radial direction so that they are in the corresponding slots 35 of the stator core 31 align radially with each other. In addition, the electrical conductor segments are 52 who have favourited the electrical conductor group 51 form, at the turn portion 54 the electrical conductor group 51 arranged parallel to each other, the order of the arrangement of the electrical conductor segments 52 at the pair of straight sections 53 the electrical conductor group 51 in the corresponding slots 35 is retained.

With the above arrangement, the electrical conductor segments 52 be bent in the same way, thereby making the stator 30th is facilitated. In addition, the electrical conductor segments 52 along the circumferential direction at the turn portion 54 are arranged, whereby the axial width of the winding portion 54 is decreased.

In the present exemplary embodiment, the essentially S-shaped bent parts are the winding sections 54 of the first electrical conductor groups 51a arranged in alignment with one another in the circumferential direction. The circumferential distance between the bent parts of the turn sections 54 of the first electrical conductor groups 51a is greater than or equal to the circumferential distance between the slots 35 of the stator core 31 and less than or equal to twice the circumferential spacing between the slots 35 . The essentially S-shaped bent parts of the winding sections 54 of the second electrical conductor group 51b are also arranged in line with one another in the circumferential direction. The circumferential distance between the bent parts of the turn sections 54 of the second electrical conductor group 51b is also greater than or equal to the circumferential distance between the slots 35 of the stator core 31 and less than or equal to twice the circumferential spacing between the slots 35 .

With the above arrangement, it becomes possible to adjust the axial width of the coil end, which consists of all winding sections 54 of the electrical conductor groups 51 is formed to reduce.

In the present exemplary embodiment, for each of the electrical conductor groups 51 one of the pair of straight sections 53 the electrical conductor group 51 in the radially outer part of a corresponding groove 35 of the stator core 31 and the other of the pair of straight sections 53 becomes in the radially inner part of another corresponding groove 35 of the stator core 31 recorded. In the bent part of the turn section 54 the electrical conductor group 51 is the radially extending part 56 formed which extends along the radial direction and in which the electrical conductor segments 52 who have favourited the electrical conductor group 51 form, are arranged aligned with one another in the circumferential direction. In addition, the radially extending parts are 56 of the winding sections 54 the first electrical conductor groups arranged in alignment with one another in the circumferential direction; and the radially extending parts 56 of the winding sections 54 of the second electrical conductor groups are also arranged in alignment with one another in the circumferential direction. The stator 30th is configured to satisfy the relationship of Rc × 2 × Tr / S N × Hc RC × 2 × π / (S / 2).

With the above configuration, it becomes possible to adjust the axial width of the coil end composed of all winding portions 54 of the electrical conductor groups 51 is formed to reduce more effectively.

In the present embodiment, between each circumferentially adjacent pair of the bent parts is the turn portions 54 of the electrical conductor groups 51 the predetermined distance C1 intended.

The bent parts of the turn sections 54 are generally made by bending the electrical conductor segments 52 educated. Hence it is on the bent parts of the turn portions 54 easier that large strains are induced and the insulating coatings 52b of the electrical conductor segments 52 are damaged than on the other parts of the winding sections 54 . With the distance C1 that between each circumferentially adjacent pair of the bent parts of the turn portions 54 of the electrical conductor groups 51 is provided, more precisely between each circumferentially adjacent pair of the radially extending parts 56 of the bent parts, however, it is still possible to provide electrical insulation between the U-phase, V-phase, and W-phase windings of the stator coil 32 to ensure.

In the present exemplary embodiment is for each of the electrical conductor groups 51 one of the pair of straight sections 53 the electrical conductor group 51 in the radially outer part of a corresponding groove 35 of the stator core 31 and the other of the pair of straight sections 53 is in the radially inner part of another corresponding groove 35 of the stator core 31 recorded. In addition, each of the electrical conductor groups is 51 configured to satisfy the relationship Wcx2 <HcxN. In addition, each of the electrical conductor groups is 51 bent so that the axially inner side surface of the turn portion 54 the electrical conductor group 51 with the circumferentially inner side surfaces of the straight sections 53 the electrical conductor group 51 is connected to the axial end face of the stator core 31 is facing.

With the above configuration, it becomes possible to adjust the axial width of the turn portions 54 of the electrical conductor groups 51 reduce more effectively.

In the present embodiment, the stator coil 32 a three-phase coil in which the U-phase, V-phase, and W-phase windings are star-connected to define the neutral point therebetween. The first and second groups of electrical conductors 51a and 51b that are an equal of the U-phase, V-phase and W-phase windings of the stator coil 32 are connected in series. In addition, the first are electrical conductor groups 51a connected closer to the star point than the second electrical conductor groups 51b (please refer 14th ).

With the above configuration, the second have electrical conductor groups 51b a higher electrical potential than the first electrical conductor groups 51a . In addition, as described above, in the present embodiment, there is in each pair of the electrical conductor groups 51 the second group of electrical conductors 51b axially within the first electrical conductor group 51a arranged and covered by this. As a result, it becomes possible to have a sufficient distance from the second electrical conductor group 51b to other electrical conductor groups 51 ensure that it leads to a different phase of the stator coil 32 as the second electrical conductor group 51b belong, thereby reducing the insulation properties of the stator coil 32 be improved.

In the present exemplary embodiment, there are winding sections 54 of each pair of the electrical conductor groups 51 the axially inner side surface of the first electrical conductor group 51a and the axially outer side surface of the second electrical conductor group 51b axially opposite and arranged at a substantially constant distance from one another. That is, the winding sections 54 the first and second electrical conductor group 51a and 51b are arranged so that they extend parallel to each other. As a result, it becomes possible to prevent the turn portions 54 the first and second electrical conductor groups 51a and 51b come into contact with each other, thereby preventing the insulating coatings 52b of the electrical conductor segments 52 representing the first and second electrical conductor groups 51a and 51b form by the contact between the winding sections 54 to be damaged. Alternatively, on the turn sections 54 of each pair of the electrical conductor groups 51 the axially inner side surface of the first electrical conductor group 51a and the axially outer side surface of the second electrical conductor group 51b be arranged in surface contact with one another. In this case, it is possible to have a larger contact area between the axially inner side surface of the first electrical conductor group 51a and the axially outer side surface of the second electrical conductor group 51b to be ensured than in the case of arrangement in point or line contact with one another; consequently it is possible to damage the insulating sheaths 52b of the electrical conductor segments 52 representing the first and second electrical conductor groups 51a and 51b form, due to contact between the winding sections 54 to suppress.

In the present embodiment, each of the electrical conductor segments comprises 52 the main body 52a formed of an electrically conductive material, and the insulating coating 52b that is the surface of the main body 52a covered. The insulating jacket 52b is formed from an electrically insulating material with clearances formed therein.

With the above configuration, those in the insulating coatings 52b of the electrical conductor segments 52 formed cavities collapse when the insulating coatings 52b Eg an external force or vibration are exposed, whereby the insulating properties of the insulating coatings 52b worsen significantly. As described above, however, in the present embodiment, the winding portions are 54 of each pair of the electrical conductor groups 51 arranged so as to axially overlap each other; between each circumferentially adjacent pair of the bent parts of the turn portions 54 of the electrical conductor groups 51 is the predetermined one distance C1 intended. Consequently it is although the insulating coating 52b is formed from the electrically insulating material with free spaces formed therein, the insulating properties of the insulating coatings are still possible 52b to secure.

In the present exemplary embodiment, the electrical conductor segments are 52 who have favourited the first electrical conductor group 51a form, at the turn sections 54 of each pair of the electrical conductor groups 51 each of the electrical conductor segments 52 who have favourited the second electrical conductor group 51b form, axially opposite and arranged at a substantially constant distance from them (see 8th ).

With the above arrangement, it is possible to prevent damage to the insulating jackets 52b of the electrical conductor segments 52 to prevent and at the same time to suppress an increase in the axial width of the coil end that consists of all winding sections 54 of the electrical conductor groups 51 is formed.

In the present exemplary embodiment, there is in each of the electrical conductor groups 51 the bent part of the winding section 54 configured to make the first bend 55 , the radially extending part 56 and the second bend 57 includes. The radius of curvature (or radius of fillet R) of the second bend 57 is set to be smaller than the radius of curvature of the first bend 55 . There is also the second bend 57 radially outside the first bend 55 (please refer 2 ).

With the above configuration, it becomes possible to make all second bends 57 of the winding sections 54 of the electrical conductor groups 51 , where the radius of curvature is relatively small and therefore it is necessary for the insulating jackets 52b of the electrical conductor segments 52 who have favourited the electrical conductor groups 51 form, is easier, during the bending of the electrical conductor groups 51 to be damaged on a radially outer part of the stator coil 32 to arrange. As a result, it becomes possible to have a sufficient distance between each circumferentially adjacent pair of the second bends 57 of the winding sections 54 of the electrical conductor groups 51 ensure, thereby reducing the insulation properties of the stator coil 32 be improved.

In the present embodiment, the winding sections are 54 of the electrical conductor groups 51 shaped so that the amount by which the winding sections 54 radially outward from the slots 35 of the stator core 31 protrude is greater than the amount by which the turn sections 54 radially inwards out of the slots 35 stick out. In other words, the stator coil 32 bulges only radially outward, not radially inward, from the slots 35 of the stator core 31 (please refer 2 ).

With the above configuration, it becomes possible to prevent the stator coil from 32 from contact with the rotor 40 close. In addition, it also becomes possible to have a sufficient distance between each circumferentially adjacent pair of the bent parts of the turn portions 54 of the electrical conductor groups 51 while suppressing an increase in the axial width of the coil end that consists of all turn portions 54 of the electrical conductor groups 51 is formed.

In the present embodiment, the rotor 40 configured so that it rotates in the specified direction of rotation (i.e. in 2 counterclockwise). In each of the electrical conductor groups 51 extends the turn portion 54 radially outwards when it is in the direction of rotation of the rotor 40 extends. That is, of the pair of peripheral ends of the turn portion 54 is the second peripheral end on the radially outer side in the rotating direction of the rotor 40 arranged in front of the first peripheral end on the radially inner side.

With the above configuration, it is in the case of cooling the stator coil 32 by oil simply for that of the rotor 40 flowing oil, through the gaps between the coil sections 54 of the electrical conductor groups 51 to get and thereby the stator coil 32 to cool effectively. Otherwise, in the case of cooling the stator coil 32 by air, it is for those of the rotor 40 flowing air simply, through the gaps between the coil sections 54 of the electrical conductor groups 51 to get. As a result, the air resistance can be decreased, thereby reducing wind noise generated during the rotation of the rotor 40 arise, be suppressed.

While the above specific embodiment has been shown and described, it will be apparent to those skilled in the art that various modifications, changes, and improvements can be made without departing from the spirit of the present disclosure.

[First modification]

In the embodiment described above, each of the electrical conductor segments comprises 52 the main body 52a formed of an electrically conductive material, and the insulating coating 52b that is the surface of the main body 52a covered. The insulating coating 52b is formed from an electrically insulating material with free spaces formed therein (see 6th ).

Alternatively, as in 15A each of the electrical conductor segments is shown 52 furthermore an insulating coating 52c without voids formed therein. In addition, the insulating coating can 52c without cavities to be provided around the surface of the main body 52a to cover, and the insulating coating 52b with clearances can be provided around the outer surface of the insulating coating 52c to cover.

As a further alternative, as in 15B shown can the insulating coating 52b with clearances to be provided around the surface of the main body 52a to cover, and the insulating coating 52c without voids can be provided around the outer surface of the insulating coating 52b to cover.

[Second modification]

In the embodiment described above, as shown in 8th , in each pair of the first and second electrical conductor groups 51a and 51b the electrical conductor segments 52 who have favourited the first electrical conductor group 51a form, are aligned in a row so that the axially inner and axially outer side surfaces of the turn portion 54 the first group of electrical conductors 51a have a flat shape; the electrical conductor segments 52 who have favourited the second electrical conductor group 51b form, are aligned in a row so that the axially inner and axially outer side surfaces of the winding section 54 the second electrical conductor group 51b have a flat shape; and the axially inner side surface of the turn portion 54 the first group of electrical conductors 51a and the axially outer side surface of the turn portion 54 the second electrical conductor group 51b are axially opposite one another and are arranged at a substantially constant distance from one another.

Alternatively, as in the 16A-16C shown in each pair of the first and second electrical conductor groups 51a and 51b the electrical conductor segments 52 who have favourited the first electrical conductor group 51a form, are aligned so that the axially inner and axially outer side surfaces of the turn portion 54 the first group of electrical conductors 51a are wavy; and the electrical conductor segments 52 who have favourited the second electrical conductor group 51b Form, can be aligned so that the axially inner and axially outer side surfaces of the turn portion 54 the second electrical conductor group 51b are wavy. In addition, in this case, it is desirable that the axially inner side surface of the turn portion 54 the first group of electrical conductors 51a and the axially outer side surface of the turn portion 54 the second electrical conductor group 51b axially opposite one another and spaced a substantially constant distance from one another, as in FIGS 16A and 16B shown. In contrast, it is undesirable that the distance between the axially inner side surface of the turn portion 54 the first group of electrical conductors 51a and the axially outer side surface of the turn portion 54 the second electrical conductor group 51b is uneven, as in 16C shown.

[Third modification]

In the embodiment described above, as shown in 12A-12B and 13th each phase winding is the stator coil 32 configured as a fully spaced distributed winding. In addition, is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed with a 7-slot division, while the winding section 54 the second electrical conductor group 51b is designed with a 5-slot division.

Each phase winding of the stator coil 32 however, it can alternatively be wound in other ways. In addition, the turn sections 54 of the electrical conductor groups 51 alternatively be designed in divisions other than the 7 and 5 divisions.

For example, as in 17A and 17B shown each phase winding of the stator coil 32 alternatively, be configured as a distributed, short pitch winding. In particular, in this example, as in 17A shown for each of the electrical conductor groups 51 (ie the first and second electrical conductor groups 51a and 51b ) one of the pair of straight sections 53 the electrical conductor group 51 in a radially outer part of a corresponding slot 35 added while the other of the pair of straight sections 53 in a radially inner part of another corresponding slot 35 is recorded. In addition, is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed in a 6-slot division, while the winding section 54 the second electrical conductor group 51b is designed in a 4-slot division. Also, as in 17B shown in each of the electrical conductor groups 51 the two straight sections 53 located at different radial positions through the winding portion 54 on the first axial side (i.e. the upper side in 17B ) of the stator core 31 tied together. On the other hand, on the second axial side (i.e. the lower side in 17B ) of the stator core 31 each corresponding pair of the straight sections 53 that lead to various of the electrical Leader groups 51 and are at the same radial position by one of the connecting sections 58 tied together. In addition, as in 17B shown each phase winding of the stator coil 32 on the stator core 31 wound in a distributed winding manner, particularly in a wave overlap winding manner.

Alternatively, as in 18A and 18B shown each phase winding of the stator coil 32 on the stator core 31 be wound in a wave winding. Especially in the in 18A The example shown is each phase winding of the stator coil 32 configured as a full pitch wave-shaped winding. In addition, is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed with a 7-slot division, while the winding section 54 the second electrical conductor group 51b is designed with a 5-slot division. On the other hand, in the in 18B Example shown each phase winding of the stator coil 32 configured as a short pitch wave-wound winding. In addition, is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed with a 6-slot division, while the winding section 54 the second electrical conductor group 51b is designed with a 4-slot division.

As a further alternative, as in 19A and 19B shown each phase winding of the stator coil 32 in an overlap winding on the stator core 31 to be wrapped. Especially in the in 19A The example shown is each phase winding of the stator coil 32 configured as a fully spaced, overlapping winding. In addition, is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed with a 7-slot division, while the winding section 54 the second electrical conductor group 51b is designed with a 5-slot division. On the other hand, in the in 19B Example shown each phase winding of the stator coil 32 configured as a short pitch lap wound winding. In addition, is for each pair of the first and second electrical conductor groups 51a and 51b the winding section 54 the first group of electrical conductors 51a formed with a 6-slot division, while the winding section 54 the second electrical conductor group 51b is designed with a 4-slot division.

[Fourth modification]

In the embodiment described above, each of the electrical conductor segments has 52 a substantially rectangular cross-sectional shape (see 6th ).

Each of the electrical conductor segments 52 however, it may alternatively also have other cross-sectional shapes, such as a circular, elliptical or barrel-shaped cross-sectional shape, as in FIG 20A-20C shown.

In addition, in the event that each of the electrical conductor segments 52 has a circular, elliptical or barrel-shaped cross-sectional shape, the radial thickness Hc and the circumferential width Wc of each of the electrical conductor segments 52 in the corresponding slots 35 of the stator core 31 like in the 20A-20C shown. More specifically, in this case, the radial thickness Hc can be increased by the maximum radial thickness in each of the electrical conductor segments 52 being represented; and the circumferential width Wc can be determined by the maximum circumferential width in each of the electric conductor segments 52 being represented.

[Fifth modification]

In the embodiment described above, the first and second electrical conductor groups are 51a and 51b that are an equal of the U-phase, V-phase and W-phase windings of the stator coil 32 form, connected in series (see 14th ).

Alternatively, as in 21 each of the U-phase, V-phase and W-phase windings of the stator coil is shown 32 a variety (e.g. two in 21 ) of pairs of electrical conductor groups 51 include. The pairs of electrical conductor groups 51 are connected in parallel to each other, and each pair of the electrical conductor groups 51 consists of a first group of electrical conductors 51a and a second group of electrical conductors 51b connected in series.

[Sixth modification]

In the embodiment described above, jumper wires can be used to separate each corresponding pair of parts of the stator coil 32 to connect distant from each other in the circumferential direction; these parts can, for example, end portions of the U-phase, V-phase and W-phase windings of the stator coil 32 , a neutral terminal, and U-phase, V-phase and W-phase connections of the stator coil 32 include. In this case, as in 22nd As shown, it is preferred through the jumper wires 100 those of the connection sections 58a and 58b of the electrical conductor segments 52 of the electrical conductor groups 51 to connect, which is radially furthest inward in the respective electrical conductor groups 51 are located. As a result, the jumper wires can be prevented from breaking 100 radially inwards or radially outwards from the electrical conductor groups 51 protrude, causing an increase in the radial size of the stator 30th suppressed and electrical insulation of the jumper wires 100 opposite the housing 20th and the rotor 40 is guaranteed. In addition, the jumper wires 100 common insulating coatings with the connection sections 58 (or the connection sections 58a and 58b of the electrical conductor segments 52 ) share.

[Seventh modification]

In the embodiment described above, the number of electrical conductor segments is N 52 that are in each of the electrical conductor groups 51 are included, set to 4. In addition, the first and second electrical conductor groups are 51a and 51b that are an equal of the U-phase, V-phase and W-phase windings of the stator coil 32 form, connected in series with each other.

Alternatively, the number N of electrical conductor segments 52 that are in each of the electrical conductor groups 51 should be set to 3. In addition, each of the U-phase, V-phase and W-phase windings of the stator coil 32 comprise four winding units which are connected in parallel to one another and each consist of a pair of the first and second electrical conductor groups 51a and 51b exist, which are connected in series with one another. In addition, the slots exist 35 of the stator core 31 , as described in the previous embodiment, from the pairs of in-phase slots Su1 and Su2, Sv1 and Sv2 and Sw1 and Sw2 (see 12A ). Each pair of the in-phase slots consists of two slots that are adjacent in the circumferential direction 35 that are equal to one of the U-phase, V-phase and W-phase windings of the stator coil 32 correspond. In each pair of in-phase slots (e.g. Su1 and Su2) are the four winding units that form the corresponding phase winding (e.g. the U-phase winding) of the stator coil 32 form, arranged so that the number of even sections 53 of the electrical conductor groups 51 of the four winding units accommodated in one (e.g., Su1) of the pair of in-phase slots 53 of the electrical conductor groups 51 of the four winding units equal to the number of straight sections received in the other (e.g. Su2) of the pair of in-phase slots 53 of the electrical conductor groups 51 of the four winding units. With the above arrangement, the four winding units can be evenly received in the pair of in-phase slots, thereby ensuring the electromagnetic balance and the circulating current in the stator 30th is suppressed.

[Eighth modification]

In the embodiment described above, the U-phase, V-phase, and W-phase windings are the stator coil 32 interconnected in a star shape. The U-phase, V-phase, and W-phase windings of the stator coil 32 however, they can alternatively also be Δ-interconnected.

A rotating electrical machine includes a polyphase armature coil that is wound on an armature core. The armature coil is formed from electrical conductor groups, each of which is a bundle of electrical conductor segments and has a pair of leg portions and a connecting portion that connects the leg portions. The connecting portion is bent radially with respect to a circumferential direction. The electrical conductor groups are paired in such a way that each pair of the electrical conductor groups consists of a first electrical conductor group and a second electrical conductor group, both of which belong to the same phase of the armature coil. The circumferential distance between the leg sections of the first electrical conductor group is greater than that between the leg sections of the second electrical conductor group. In each pair of the electrical conductor groups, the terminal portions of the first and second electrical conductor groups are arranged so that they axially overlap one another.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP 5702179 B2 [0002]

Claims (11)

Rotating electrical machine (10) with an armature (30), the armature having an annular armature core (31) and a polyphase armature coil (32) which is wound on the armature core, wherein: the armature core has a plurality of slits (35) arranged in a circumferential direction thereof; the armature coil is formed from a plurality of interconnected electrical conductor groups (51), each of the plurality of electrical conductor groups being formed from a bundle of a plurality of electrical conductor segments (52); each of the plurality of electrical conductor groups is substantially U-shaped to have a pair of leg portions (53) and a connecting portion (54), the pair of leg portions each being received in a corresponding pair of the slots of the armature core and at different radial positions is disposed in the respective slots, the connecting portion extending on an axial side of the armature core to connect the pair of leg portions, the connecting portion having a bent part (55, 56, 57) bent radially with respect to the circumferential direction is; the plurality of electrical conductor groups are paired so that each pair of electrical conductor groups consists of a first electrical conductor group (51a) and a second electrical conductor group (51b) both of which belong to a same phase of the armature coil; a circumferential distance between the pair of leg portions of the first electrical conductor group is greater than a circumferential distance between the pair of leg portions of the second electrical conductor group; and in each pair of the electrical conductor groups, the connecting portions of the first and second electrical conductor groups are arranged so as to axially overlap. Rotating electrical machine according to Claim 1 wherein: for each of the electrical conductor groups, the electrical conductor segments constituting the electrical conductor group are arranged on the pair of leg portions of the electrical conductor group in a predetermined arrangement order in a radial direction so as to be radially aligned with each other in the corresponding slots of the armature core; and at the connecting portion of the electrical conductor group, the electrical conductor segments which form the electrical conductor group are arranged parallel to one another, the order of arrangement of the electrical conductor segments on the pair of leg portions of the electrical conductor group in the corresponding slots being maintained. Rotating electrical machine according to Claim 1 or 2 wherein: the bent parts of the connecting portions of the first electrical conductor groups are arranged in the circumferential direction in alignment with one another; a circumferential distance between the bent parts of the connecting portions of the first electrical conductor groups is greater than or equal to a circumferential distance between the slots of the armature core and less than or equal to twice the circumferential distance between the slots; the bent parts of the connecting portions of the second electrical conductor groups are also arranged in alignment with one another in the circumferential direction; and a circumferential distance between the bent parts of the connecting portions of the second electrical conductor groups is also greater than or equal to the circumferential distance between the slots of the armature core and less than or equal to twice the circumferential distance between the slots. Rotating electrical machine according to one of the Claims 1 - 3 wherein: for each of the electrical conductor groups, one of the pair of leg portions of the electrical conductor group is received in a radially outer portion of a corresponding slot of the armature core and the other of the pair of leg portions is received in a radially inner portion of another corresponding slot of the armature core; for each of the electrical conductor groups in the bent part of the connecting section of the electrical conductor group, a radially extending part (56) is formed which extends along a radial direction and in which the electrical conductor segments forming the electrical conductor group are arranged in alignment with one another in the circumferential direction; the radially extending parts of the connecting portions of the first electrical conductor groups are arranged in alignment with one another in the circumferential direction, and the radially extending parts of the connecting portions of the second electrical conductor groups are arranged in alignment with one another in the circumferential direction; and the following relationship is fulfilled: $$\text{Rc}\times 2\times \mathrm{\pi }/\text{S.}\le \text{N}\times \text{Hc}\le \text{Rc}\times 2\times \mathrm{\pi }/\left(\text{S.}/2\right)$$

where Rc is a distance from a central axis of the armature core to a radial center of each of the slots, S is the number of slots formed in the armature core, N is the number of electrical conductor segments included in each of the electrical conductor groups and Hc is a radial thickness of each of the electrical conductor segments in the corresponding slots of the armature core. Rotating electrical machine according to one of the Claims 1 - 4th wherein: a spacing (C1) is provided between each circumferentially adjacent pair of the bent parts of the connecting portions of the electrical conductor groups. Rotating electrical machine according to one of the Claims 1 - 5 wherein: for each of the electrical conductor groups, one of the pair of leg portions of the electrical conductor group is received in a radially outer portion of a corresponding slot of the armature core and the other of the pair of leg portions is received in a radially inner portion of another corresponding slot of the armature core; and the following relationship is fulfilled: $$\text{WC}\times 2<\text{Hc}\times \text{N},$$

where Wc is a circumferential width of each of the electrical conductor segments in the corresponding slots of the armature core, Hc is a radial thickness of each of the electrical conductor segments in the corresponding slots of the armature core, and N is the number of the electrical conductor segments included in each of the electrical conductor groups. Rotating electrical machine according to one of the Claims 1 - 6th wherein: the armature coil is a three-phase coil having three phase windings star-connected to define a neutral point therebetween; the first and second groups of electrical conductors forming the same one of the phase windings of the armature coil are connected in series with each other; and the first electrical conductor groups are connected closer to the star point than the second electrical conductor groups. Rotating electrical machine according to one of the Claims 1 - 7th wherein: at the connecting portions of each pair of the electrical conductor groups, an axially inner side surface of the first electrical conductor group and an axially outer side surface of the second electrical conductor group are arranged in surface contact with each other. Rotating electrical machine according to one of the Claims 1 - 8th wherein: each of the electrical conductor segments has a main body (52a) formed of an electrically conductive material and an insulating coating (52b) covering a surface of the main body; and the insulating coating is made of an electrically insulating material with clearances formed therein. Rotating electrical machine according to one of the Claims 1 - 7th and 9 , wherein: at the connecting portions of each pair of the electrical conductor groups, the electrical conductor segments that form the first electrical conductor group are each axially opposite to the electrical conductor segments that form the second electrical conductor group and are arranged at a substantially constant distance therefrom. Rotating electrical machine according to one of the Claims 1 - 10 wherein: each of the electrical conductor groups consists of a bundle of three electrical conductor segments; the armature coil is a three-phase coil in which three phase windings are connected in a star connection; each of the phase windings of the armature coil comprises four winding units connected in parallel to each other, each comprising a pair of the first and second electrical conductor groups connected in series with each other; the plurality of slots of the armature core consists of pairs of in-phase slots (Su1, Su2, Sv1, Sv2, Sw1, Sw2), each pair of in-phase slots consisting of two circumferentially adjacent slots which correspond to a same one of the phase windings of the armature coil; and in each pair of the in-phase slots, the four winding units which form the corresponding phase winding of the armature coil are arranged so that the number of leg portions of the electrical conductor groups of the four winding units received in one of the pair of in-phase slots is equal to the number of Is leg portions of the electrical conductor groups of the four winding units received in the other of the pair of in-phase slots.

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